Text (and icon) sizing has two options in AutoREALM.
The first is that it is placed absolutely the same size, regardless of the zoom level. That means that if you are zoom in on a map, the text in the text toolbar will be much smaller than the size of the text after it is placed. This keeps your text size absolute with regard to the zoom level.
The second option is to place the text on the map the same size as it actually appears in the text toolbar. This means that if you zoom in, the text size after placement will match that in the toolbar, but if you zoom back out, it will be much smaller. This keeps the text size relative to the zoom level.
You can toggle between the two choices for icons and text under the General Settings.